As disclosed in early known arts, for example, U.S. Pat. Nos. 3,869,429 and 3,869,430, wholly aromatic polyamide filaments are manufactured by a series of processes including: a process of preparing wholly aromatic polyamide polymer by polymerizing aromatic diamine and aromatic diacid chloride in a polymerization solvent containing N-methyl-2-pyrrolidone; a process of preparing a spinning liquid dope by dissolving the prepared polyamide polymer in a concentrated sulfuric acid solvent; a process of forming filaments by extruding the spinning liquid dope through spinnerets and passing the spun material through a non-coagulation fluid layer into a coagulant tank; and a process of refining the resulting filaments by washing, drying and heat treatment processes.
FIG. 1 is a schematic view illustrating a method of manufacturing wholly aromatic polyamide filament by conventional dry-wet spinning process.
As to a conventional process of manufacturing wholly aromatic polyamide filament as illustrated in FIG. 2, since aromatic diacid chloride A as polymeric monomer and a polymerization solvent B containing aromatic diamine as another polymeric monomer are individually introduced into a polymerization reactor 20 through each of corresponding feed pipes 11 which are contiguous with or separated from each other, both of the monomers put into the reactor 20 do not mingle together very well immediately after introducing the monomers, thus, are not polymerized uniformly or homogeneously over all of area of the reactor 20.
For that reason, the conventional process has a disadvantage of increasing deviation in degree of polymerization for wholly aromatic polyamide polymer, thereby causing a problem that physical properties, especially, strength and modulus of wholly aromatic polyamide filament are deteriorated.
As a result of intensive study and investigation made by the present inventor in order to solve the foregoing problem, the present invention has been suggested to produce novel wholly aromatic polyamide filament with improved strength and modulus.